CRP and LDH levels as biomarkers in thymic epithelial tumors: twenty years single center experience

Background:

Thymic epithelial tumors are the most common mediastinal tumors. Surgery is the mainstay of treatment and complete resection provides the best survival rate. Nevertheless, advanced tumors may require multimodal therapy and additional prognostic factors beyond tumor stage and histological classification might help to risk-stratify patients and personalize the treatment course.

Material and Method:

Between 1998 and 2018 220 patients with thymic epithelial tumors were operated in our center. The preoperative C-reactive protein (CRP) and lactate dehydrogenase (LDH) levels as well as clinical follow-up were retrospectively collected and the association of circulating biomarkers with clinicopathological parameters and their impact on overall survival was analyzed.

Result:

124 (56%) male and 96 (44%) female patients were included in the study with the median age of 62 (range 15 – 84) years at the time of operation. 33 patients (including 13 male patients) suffered from myasthenia gravis. Thymic carcinoma and neuroendocrine tumors were associated with high CRP (> 1 mg/dl) when compared to thymoma cases (30% and 44% vs. 11%, p = 0.0005). Increased LDH level was found thymic neuroendocrine tumors when compared to thymoma or thymic carcinoma (336, 218 and 218 U/L, p = 0.002). Thymoma patients had a significantly better disease specific median overall survival when compared to thymic carcinoma and neuroendocrine tumors (not reached, 137 and 163 months, respectively, p = 0.028). Elevated CRP (> 1 mg/dl) did not show prognostic power for overall survival. In contrast, increased preoperative LDH level (> 240 U/L) showed a tendency for association with poorer outcome in thymus carcinoma (HR 0.21, p = 0.062).

Conclusion:

Increased CRP associates with thymic carcinoma and neuroendocrine tumors while LDH increase is characteristic of neuroendocrine tumors. Importantly, preoperative LDH levels carry prognostic information in thymic carcinoma and could be used to risk stratify surgically treated patients in multimodal treatment settings.